INS and obesity due to melanocortin 4 receptor deficiency: The results of this study showed that triple-Tg mice fed a high-fat and high-sucrose diet showed early symptoms of diabetes including obesity, impaired glucose tolerance, insulin resistance, abnormal insulin secretion and slightly elevated plasma glucose levels (Masuzaki et al., 2001; Paterson et al., 2004; Winzell & Ahrén, 2005).